title: Influence of estrogen therapy on calcium, phosphorus, and other regulatory hormones in postmenopausal women: the MESA study.
abstract: BACKGROUND
  Estrogen therapy (ET) is associated with lower serum calcium and phosphorus concentrations and is known to increase bone mineral density (BMD). Other biomarkers of mineral metabolism may help understand the biological basis of these actions.
  
  
  METHODS
  We studied 2767 postmenopausal women in the Multi-Ethnic Study of Atherosclerosis, 862 (31%) of whom were using ET. We measured serum concentrations of calcium, phosphorus, 25-hydroxyvitamin D, 24,25-dihydoxyvitamin D, and fibroblast growth factor-23 and urinary fractional excretion of calcium (FEca) and phosphorus (FEphos). We examined the associations of ET with each biomarker. In addition, we tested whether the adjustment for biomarkers attenuated the association of ET with lumbar BMD measured by abdominal computed tomography in a subset of 810 women.
  
  
  RESULTS
  In adjusted models, women who used ET were younger in age [62 (SD 8) vs 66 (9) y, P < .001], had lower mean serum calcium [-13 mg/dL (95% confidence interval [CI] -0.17, -0.10), P < .001] and lower FEca [-0.15% (95% CI -0.21, -0.09), P < .001]. Mean serum phosphorus was lower [-0.19 mg/dL (95% CI -0.23, -0.15), P < .001] and FEphos [0.56% (95% CI 0.16, 0.96), P = .007] was higher in women on ET. Mean 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D were higher [1.52 ng/dL (95% CI 0.57, 2.47), P = .002, and 0.26 ng/mL (95% CI 0.03, 0.48), P = .03, respectively] in women who used ET. Mean PTH and fibroblast growth factor-23 did not differ significantly by the use of ET. ET use was strongly associated with higher lumbar BMD [12.75 mg/cm³ (95% CI 7.77-17.73), P < .001]; however, mineral metabolism measures did not meaningfully alter this association.
  
  
  CONCLUSIONS
  In a multiethnic cohort of postmenopausal women, ET use was associated with lower serum calcium, lower FEca, lower serum phosphorus, and higher FEphos, suggesting these associations are attributable to increased calcium intake into bone and increased urinary phosphorus excretion. ET use was also associated with greater concentrations of vitamin D metabolites. ET-associated differences in these mineral metabolism measures did not meaningfully attenuate the strong association between ET use and lumbar BMD.
authors.affiliation: MD, MAS, Kidney Research Institute, University of Washington, 908 Jefferson Street, Third Floor, Seattle, WA 98104. nisha.bansal@gmail.com.
authors.forename: Nisha
authors.initials: N
authors.lastname: Bansal
authors.forename: Ronit
authors.initials: R
authors.lastname: Katz
authors.forename: Ian H
authors.initials: IH
authors.lastname: de Boer
authors.forename: Bryan
authors.initials: B
authors.lastname: Kestenbaum
authors.forename: David S
authors.initials: DS
authors.lastname: Siscovick
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Hoofnagle
authors.forename: Russell
authors.initials: R
authors.lastname: Tracy
authors.forename: Gail A
authors.initials: GA
authors.lastname: Laughlin
authors.forename: Michael H
authors.initials: MH
authors.lastname: Criqui
authors.forename: Mathew J
authors.initials: MJ
authors.lastname: Budoff
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Joachim H
authors.initials: JH
authors.lastname: Ix
mesh_terms: D015650:24,25-Dihydroxyvitamin D 3 / Q000097:blood / Q000378:metabolism; D015652:25-Hydroxyvitamin D 2 / Q000097:blood / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood / Q000378:metabolism / Q000652:urine; D015519:Bone Density / Q000187:drug effects; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism; D002112:Calcifediol / Q000097:blood / Q000378:metabolism; D002118:Calcium / Q000097:blood* / Q000652:urine; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004872:Ergocalciferols / Q000097:blood / Q000378:metabolism; D015914:Estrogen Replacement Therapy; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000000981:diagnostic imaging / Q000378:metabolism / Q000517:prevention & control*; D010758:Phosphorus / Q000097:blood* / Q000652:urine; D011859:Radiography; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism
chemical_list: D015415:Biomarkers; D004872:Ergocalciferols; D014807:Vitamin D; D015652:25-Hydroxyvitamin D 2; D010758:Phosphorus; D015650:24,25-Dihydroxyvitamin D 3; D005346:Fibroblast Growth Factors; C028140:24,25-dihydroxyvitamin D2; D000089703:Fibroblast Growth Factor-23; D002112:Calcifediol; D002118:Calcium